On your Mac, when you open System Preferences it freezes straight away.
- Click the Finder icon in the Dock (smiley face icon).
- On the top menu click Go -> Go to Folder…
- Type in ~/Library/Preferences and press Enter.
- Look for a file called com.apple.desktop.plist and move it to the Trash.
- Log back in (you will need to set your Desktop wallpaper again).